The rapid urbanization in China has led to severe agricultural non-point source pollution, threatening sustainable development. This study investigates the impact of new urbanization policies on controlling agricultural non-point source pollution and explores the underlying mechanisms. Utilizing panel data from 159 Chinese prefecture-level cities (2007-2020) and employing a multi-period difference-in-differences method, we find that new urbanization policies significantly reduce agricultural non-point source pollution, particularly in eastern regions and larger cities. Our analysis reveals that strengthened environmental regulations and advancements in agricultural green technologies are crucial pathways through which these policies influence pollution control. This research contributes to the understanding of policy effectiveness in addressing environmental challenges associated with urbanization and provides evidence-based recommendations for sustainable urban-rural development in China.